1 /*
2  *	NANO7240 SBC Watchdog device driver
3  *
4  *	Based on w83877f.c by Scott Jennings,
5  *
6  *	This program is free software; you can redistribute it and/or modify
7  *	it under the terms of the GNU General Public License version 2 as
8  *	published by the Free Software Foundation;
9  *
10  *	Software distributed under the License is distributed on an "AS IS"
11  *	basis, WITHOUT WARRANTY OF ANY KIND, either express or
12  *	implied. See the License for the specific language governing
13  *	rights and limitations under the License.
14  *
15  *	(c) Copyright 2007  Gilles GIGAN <gilles.gigan@jcu.edu.au>
16  *
17  */
18 
19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20 
21 #include <linux/fs.h>
22 #include <linux/init.h>
23 #include <linux/ioport.h>
24 #include <linux/jiffies.h>
25 #include <linux/module.h>
26 #include <linux/moduleparam.h>
27 #include <linux/miscdevice.h>
28 #include <linux/notifier.h>
29 #include <linux/reboot.h>
30 #include <linux/types.h>
31 #include <linux/watchdog.h>
32 #include <linux/io.h>
33 #include <linux/uaccess.h>
34 #include <linux/atomic.h>
35 
36 #define SBC7240_ENABLE_PORT		0x443
37 #define SBC7240_DISABLE_PORT		0x043
38 #define SBC7240_SET_TIMEOUT_PORT	SBC7240_ENABLE_PORT
39 #define SBC7240_MAGIC_CHAR		'V'
40 
41 #define SBC7240_TIMEOUT		30
42 #define SBC7240_MAX_TIMEOUT		255
43 static int timeout = SBC7240_TIMEOUT;	/* in seconds */
44 module_param(timeout, int, 0);
45 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<="
46 		 __MODULE_STRING(SBC7240_MAX_TIMEOUT) ", default="
47 		 __MODULE_STRING(SBC7240_TIMEOUT) ")");
48 
49 static bool nowayout = WATCHDOG_NOWAYOUT;
50 module_param(nowayout, bool, 0);
51 MODULE_PARM_DESC(nowayout, "Disable watchdog when closing device file");
52 
53 #define SBC7240_OPEN_STATUS_BIT		0
54 #define SBC7240_ENABLED_STATUS_BIT	1
55 #define SBC7240_EXPECT_CLOSE_STATUS_BIT	2
56 static unsigned long wdt_status;
57 
58 /*
59  * Utility routines
60  */
61 
62 static void wdt_disable(void)
63 {
64 	/* disable the watchdog */
65 	if (test_and_clear_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
66 		inb_p(SBC7240_DISABLE_PORT);
67 		pr_info("Watchdog timer is now disabled\n");
68 	}
69 }
70 
71 static void wdt_enable(void)
72 {
73 	/* enable the watchdog */
74 	if (!test_and_set_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
75 		inb_p(SBC7240_ENABLE_PORT);
76 		pr_info("Watchdog timer is now enabled\n");
77 	}
78 }
79 
80 static int wdt_set_timeout(int t)
81 {
82 	if (t < 1 || t > SBC7240_MAX_TIMEOUT) {
83 		pr_err("timeout value must be 1<=x<=%d\n", SBC7240_MAX_TIMEOUT);
84 		return -1;
85 	}
86 	/* set the timeout */
87 	outb_p((unsigned)t, SBC7240_SET_TIMEOUT_PORT);
88 	timeout = t;
89 	pr_info("timeout set to %d seconds\n", t);
90 	return 0;
91 }
92 
93 /* Whack the dog */
94 static inline void wdt_keepalive(void)
95 {
96 	if (test_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status))
97 		inb_p(SBC7240_ENABLE_PORT);
98 }
99 
100 /*
101  * /dev/watchdog handling
102  */
103 static ssize_t fop_write(struct file *file, const char __user *buf,
104 			 size_t count, loff_t *ppos)
105 {
106 	size_t i;
107 	char c;
108 
109 	if (count) {
110 		if (!nowayout) {
111 			clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
112 				&wdt_status);
113 
114 			/* is there a magic char ? */
115 			for (i = 0; i != count; i++) {
116 				if (get_user(c, buf + i))
117 					return -EFAULT;
118 				if (c == SBC7240_MAGIC_CHAR) {
119 					set_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
120 						&wdt_status);
121 					break;
122 				}
123 			}
124 		}
125 
126 		wdt_keepalive();
127 	}
128 
129 	return count;
130 }
131 
132 static int fop_open(struct inode *inode, struct file *file)
133 {
134 	if (test_and_set_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status))
135 		return -EBUSY;
136 
137 	wdt_enable();
138 
139 	return nonseekable_open(inode, file);
140 }
141 
142 static int fop_close(struct inode *inode, struct file *file)
143 {
144 	if (test_and_clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT, &wdt_status)
145 	    || !nowayout) {
146 		wdt_disable();
147 	} else {
148 		pr_crit("Unexpected close, not stopping watchdog!\n");
149 		wdt_keepalive();
150 	}
151 
152 	clear_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status);
153 	return 0;
154 }
155 
156 static const struct watchdog_info ident = {
157 	.options = WDIOF_KEEPALIVEPING|
158 		   WDIOF_SETTIMEOUT|
159 		   WDIOF_MAGICCLOSE,
160 	.firmware_version = 1,
161 	.identity = "SBC7240",
162 };
163 
164 
165 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
166 {
167 	switch (cmd) {
168 	case WDIOC_GETSUPPORT:
169 		return copy_to_user((void __user *)arg, &ident, sizeof(ident))
170 						 ? -EFAULT : 0;
171 	case WDIOC_GETSTATUS:
172 	case WDIOC_GETBOOTSTATUS:
173 		return put_user(0, (int __user *)arg);
174 	case WDIOC_SETOPTIONS:
175 	{
176 		int options;
177 		int retval = -EINVAL;
178 
179 		if (get_user(options, (int __user *)arg))
180 			return -EFAULT;
181 
182 		if (options & WDIOS_DISABLECARD) {
183 			wdt_disable();
184 			retval = 0;
185 		}
186 
187 		if (options & WDIOS_ENABLECARD) {
188 			wdt_enable();
189 			retval = 0;
190 		}
191 
192 		return retval;
193 	}
194 	case WDIOC_KEEPALIVE:
195 		wdt_keepalive();
196 		return 0;
197 	case WDIOC_SETTIMEOUT:
198 	{
199 		int new_timeout;
200 
201 		if (get_user(new_timeout, (int __user *)arg))
202 			return -EFAULT;
203 
204 		if (wdt_set_timeout(new_timeout))
205 			return -EINVAL;
206 
207 		/* Fall through */
208 	}
209 	case WDIOC_GETTIMEOUT:
210 		return put_user(timeout, (int __user *)arg);
211 	default:
212 		return -ENOTTY;
213 	}
214 }
215 
216 static const struct file_operations wdt_fops = {
217 	.owner = THIS_MODULE,
218 	.llseek = no_llseek,
219 	.write = fop_write,
220 	.open = fop_open,
221 	.release = fop_close,
222 	.unlocked_ioctl = fop_ioctl,
223 };
224 
225 static struct miscdevice wdt_miscdev = {
226 	.minor = WATCHDOG_MINOR,
227 	.name = "watchdog",
228 	.fops = &wdt_fops,
229 };
230 
231 /*
232  *	Notifier for system down
233  */
234 
235 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
236 			  void *unused)
237 {
238 	if (code == SYS_DOWN || code == SYS_HALT)
239 		wdt_disable();
240 	return NOTIFY_DONE;
241 }
242 
243 static struct notifier_block wdt_notifier = {
244 	.notifier_call = wdt_notify_sys,
245 };
246 
247 static void __exit sbc7240_wdt_unload(void)
248 {
249 	pr_info("Removing watchdog\n");
250 	misc_deregister(&wdt_miscdev);
251 
252 	unregister_reboot_notifier(&wdt_notifier);
253 	release_region(SBC7240_ENABLE_PORT, 1);
254 }
255 
256 static int __init sbc7240_wdt_init(void)
257 {
258 	int rc = -EBUSY;
259 
260 	if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
261 		pr_err("I/O address 0x%04x already in use\n",
262 		       SBC7240_ENABLE_PORT);
263 		rc = -EIO;
264 		goto err_out;
265 	}
266 
267 	/* The IO port 0x043 used to disable the watchdog
268 	 * is already claimed by the system timer, so we
269 	 * can't request_region() it ...*/
270 
271 	if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
272 		timeout = SBC7240_TIMEOUT;
273 		pr_info("timeout value must be 1<=x<=%d, using %d\n",
274 			SBC7240_MAX_TIMEOUT, timeout);
275 	}
276 	wdt_set_timeout(timeout);
277 	wdt_disable();
278 
279 	rc = register_reboot_notifier(&wdt_notifier);
280 	if (rc) {
281 		pr_err("cannot register reboot notifier (err=%d)\n", rc);
282 		goto err_out_region;
283 	}
284 
285 	rc = misc_register(&wdt_miscdev);
286 	if (rc) {
287 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
288 		       wdt_miscdev.minor, rc);
289 		goto err_out_reboot_notifier;
290 	}
291 
292 	pr_info("Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
293 		nowayout);
294 
295 	return 0;
296 
297 err_out_reboot_notifier:
298 	unregister_reboot_notifier(&wdt_notifier);
299 err_out_region:
300 	release_region(SBC7240_ENABLE_PORT, 1);
301 err_out:
302 	return rc;
303 }
304 
305 module_init(sbc7240_wdt_init);
306 module_exit(sbc7240_wdt_unload);
307 
308 MODULE_AUTHOR("Gilles Gigan");
309 MODULE_DESCRIPTION("Watchdog device driver for single board"
310 		   " computers EPIC Nano 7240 from iEi");
311 MODULE_LICENSE("GPL");
312